1. Field of Invention
The present invention relates in general to the field of electrostatic ink jet printers. More particularly, the present invention relates to a disposable ink jet cartridge which forms part of a printer head which is mounted to move transversely back and forth across the width of a recording paper. Still more particularly, the present invention relates to an ink jet printer in which a replaceable cartridge contains not only the ink supply but also the ink jet itself.
2. Prior Art
Prior art electrostatic ink jet printing systems include an ink jet nozzle, a supply of conductive ink, a metallized surface upon which recording paper is placed, and a high voltage supply connected between the conductive ink and the metallized surface. Upon application of the voltage differential, the ink is drawn from the ink jet nozzle toward the metallized surface. Since the paper is interposed between the ink jet nozzle and the metallized surface, the ink is deposited on the paper so long as the voltage is applied. Thus, either the paper, the ink jet nozzle, or both have to be moved in order to print any comprehensible information.
Many problems exist in prior art electrostatic ink jet printing systems. For example, since the reservoir containing the ink supply has to be periodically refilled, the reservoir must include an opening means for adding additional ink. Oftentimes, during refilling, outside contaminents enter the opening along with the ink. Also, the container for storing the refill supply of ink may include dried ink residue which can be introduced to the system when the reservoir is refilled. The introduction of such contaminents to the ink supply reservoir often results in clogging of the ink jet nozzle. Further, the task of refilling the ink reservoir is a messy job.
Prior art systems exhibit additional problems due to variations in the level of ink in the supply reservoir. These variations cause changes in the ink head pressure to the jet nozzle and result in variations in the density and quality of the printing produced.
3. Objects
It is the general object of the present invention to overcome many of the above mentioned drawbacks of the prior art by providing a disposable ink jet cartridge which contains therein not only an ink supply, but also the jet nozzle itself.
It is another object of the present invention to provide such a cartridge whose internal head pressure at the jet nozzle is maintained at a constant level by a hydrostatic controller.
It is still another object of the present invention to provide an ink cartridge which includes means for transferring an enclosed ink supply from one compartment over a fixed height wall into another compartment to thereby maintain a constant head pressure in the other compartment.
It is an additional object of the present invention to provide an ink jet cartridge whose ink supply is sealed from contamination by external particulants.
It is still an additional object of the present invention to provide an ink jet cartridge which maintains constant hydrostatic pressure to an integral nozzle and which automatically vents the ink supply to allow air to replace expended ink.
It is yet another object of the present invention to provide an ink jet cartridge which forms part of a printer head which is mounted to move transversely back and forth across the width of a recording paper.
It is a further object of the present invention to provide a multi-compartmentalized ink jet cartridge including an integral electrostatic on-demand ink jet nozzle wherein a constant head pressure of ink is maintained in the compartment which supplies the jet nozzle with ink.
These and other objects of the present invention will become more apparent upon a studious consideration of the accompanying drawings in combination with a reading of the following detailed description of the preferred embodiments.